Immunity Duration and Catch-Up Program Affect HPV Vaccination Cost

Action Points

Explain to patients that this study suggests that vaccine effectiveness and the upper age limit of catch-up programs will significantly influence the cost vaccination against human papillomavirus.

Note that the findings were based on mathematical models, not human testing.

BOSTON, Aug. 20 -- The cost-effectiveness of immunization against human papillomavirus hinges on the length of time the vaccine is effective and the ability to reach targeted populations, data from a statistical model suggest.

Changes in key variables resulted in a range of $43,600 to $150,700 per quality-adjusted life-year (QALY) gained by vaccination, Jane J. Kim, Ph.D., and Sue J. Goldie, M.D., of the Harvard School of Public Health, reported in the Aug. 21 issue of the New England Journal of Medicine.

"The cost-effectiveness of HPV vaccination in the United States will likely be optimized by achieving universal coverage in young adolescent girls and targeting initial catch-up efforts to girls and women younger than 21," the authors said.

"Optimal synergies between vaccination and screening will involve revisions to current screening practice," they noted.

Vaccines against HPV-16 and HPV-18 have demonstrated efficacy for preventing infections and cervical lesions related to those strains in previously uninfected girls and women. However, several key questions about appropriate target audiences for vaccination remain unanswered, the authors said.

Most authorities agree that routine immunization should be targeted to girls of about age 12, Drs. Kim and Goldie continued. However, recommended temporary catch-up programs to immunize older girls and women have upper age limits ranging from 18 to 26.

Because HPV vaccination's impact on cervical cancer incidence will not been seen for decades, decisions regarding vaccination policy will have to rely on intermediate outcomes, the authors said.

Mathematical models that synthesize the best-available data can project outcomes beyond those reported from clinical trials, provide insight to key influences of cost-effectiveness, and be revised as new information becomes available.

Building on data from previous studies, the authors evaluated the cost-effectiveness of vaccinating 12-year-old girls and of temporary catch-up programs.

Catch-up programs with upper age limits of 18, 21, and 26 were examined.

Other factors considered in the modeling process included the benefits of averting other cancers associated with HPV-16 and HPV-18, prevention of genital warts and juvenile-onset recurrent respiratory papillomatosis caused by HPV-6 and HPV-11 (which are included in the U.S. vaccine), duration of immunity, and future screening practices.

Immunization strategies were evaluated within the context of cytology-based screening as practiced in the U.S.

The analysis showed that immunization of 12-year-old girls resulting in lifetime immunity would cost $43,600 per QALY compared with the current screening practice.

Temporary catch-up programs would cost $97,300 per QALY if extended to 18-year-olds, $120,400 if extended to 21-year-olds, and $152,700 if extended to 26-year-olds.

If immunity waned 10 years after vaccination, the cost of immunizing 12-year-old girls increased to $140,000 per QALY.

Moreover, catch-up strategies were less effective than screening alone.

Cost-effectiveness became more favorable when the benefits of averting other health conditions were included and when screening was delayed and performed at less frequent intervals using more sensitive tests.

If vaccinated girls were screened more frequently in adulthood, the cost-effectiveness of immunization became less favorable.

The study was supported by the National Cancer Institute, the CDC, the American Cancer Society, and the Bill and Melinda Gates Foundation.

The authors declared no potential conflicts of interest.

Reviewed by Robert Jasmer, MD Associate Clinical Professor of Medicine, University of California, San Francisco

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